The main objective of the research is to understand how we process and remember auditory information. The goal is to develop a psychological model of speech perception and nonverbal auditory processing. The research has been directed at understanding the psychological processes and memory structures in deriving meaning from sound. The study of speech recognition is carried out in a backward recognition masking task. Observers identify a speech sound followed after a variable silent interval by a second sound. Both sounds are presented at a normal listening intensity. This paradigm allows one to study the dynamics of speech recognition and the processes and structures involved. This research is also concerned with the operations of attention and limited capacity in auditory information processing. Subjects are asked to count the numbers of sounds coming in the same auditory channel or alternating between channels. Channels might correspond to the two ears, frequency ranges, or intensity ranges. The accuracy in counting performance provides information about the temporal course of deriving meaning from sound and the operation of attention in information processing.